Development of temporomandibular joint ankylosis in rats: a preliminary experimental study

The objective of this study was to evaluate a model for the development of temporomandibular joint ankylosis in rats using disc removal and articular damage. In 30 adult male Wistar rats, articular damage was induced and disc removal performed in the right joint to induce ankylosis. The rats were divided into groups according to the time of killing (7, 15, 30, 60 and 90 days). Maximal mouth opening, mandibular deviation, initial and final weights, and duration of surgery were recorded and evaluated. After death, the joints were submitted to histological study in order to score the ankylosis. The mean duration of surgery was 14.23 min. Mean difference between initial and final maximal mouth opening was 3.38 mm, being greatest at the 15-day evaluation and lowest at 90 days, and was statistically significant at 15 days (p=0.043), 30 days (p=0.027) and 60 days (p=0.027). No mandibular deviation was observed at any of the evaluation times. Histological scores increased with time of evaluation from 7 to 30 days, when they started to fall. This study model permitted the development of fibrous ankylosis in the majority of the animals, and no bony bridge was observed between the mandibular condyle and the temporal bone.